The silent enemy you didn't know you were fighting is called negativity.
The undeniable truth is that any form of negativity consumes energy that you could invest into more productive and useful things.
As a creative, you need to learn to allocate your energy. And there is only a limited amount of energy every day. What you spend energy on is your choice.
Any form of negativity (self-doubts, fear, overthinking) consumes significant amounts of energy. So you are better of to radically protect your energy from negativity. And the places to look for are your own mind, the people around you, and the things you consume.
There are more useful things you can do with your energy. And negativity in itself is not contributing to anything worth pursuing.